1. Technical Field
The present disclosure relates to a crystal controlled oscillator and an oscillating device using the crystal controlled oscillator. The crystal controlled oscillator detects a temperature of atmosphere where a crystal unit is placed and controls a heating unit based on a detection result of the temperature, so as to make the temperature of the atmosphere uniform.
2. Description of the Related Art
Usually, when a crystal controlled oscillator is incorporated in an application requiring sufficiently high frequency stability, an oven controlled crystal oscillator (OCXO) is ordinarily used. In temperature control by the OCXO, a thermistor is employed as a temperature sensor, and discrete parts such as an operational amplifier, a resistor, and a capacitor are employed. However, due to individual variation and long-term changes in analog parts, it was not possible to carry out temperature control within ±20 m° C., for example.
However, in base stations and relay stations, for example, use of inexpensive clock signals with significantly high stability is being demanded, the handling of which would consequently be a predictably difficult situation with the conventional OCXO.
Japanese Unexamined Patent Application Publication No. 2012-170050 discloses a Temperature Compensated Crystal Oscillator (TCXO) that recognizes a value according to a difference between oscillation frequencies of two crystal units as a temperature detection value and corrects a set frequency of the oscillating device according to the temperature detection value. However, the method relates to a temperature compensated crystal oscillator (TCXO) that corrects an oscillation frequency based on temperature detection but does not relate to the OCXO.